KR-20260066871-A - Preprocessing method for anodizing of alumium alloy

KR20260066871AKR 20260066871 AKR20260066871 AKR 20260066871AKR-20260066871-A

Abstract

The present invention relates to a pretreatment method for surface treatment of an aluminum alloy, and more specifically, to a cathodic oxidation treatment method for an aluminum alloy to remove silica (Si) components included in the aluminum alloy composition that cause defects during surface treatment, in order to reduce surface treatment defects caused by the influence of the alloy composition during anodic oxidation treatment of the aluminum alloy material. According to the present invention, substances such as silicon that are not ionized by substances other than hydrofluoric acid can be electrically reduced and removed, so that porous POREs of aluminum oxide having a size of several hundred nm can be uniformly formed on the surface during chemical surface treatment of aluminum. In addition, an additional effect according to the present invention is that the non-uniformity of the aluminum oxide film is eliminated during the anodic oxidation treatment of the aluminum alloy, thereby making the formation of porous PORE uniform, which enables the formation of a uniform colored layer by dye.

Inventors

손병기
심그린
권수현
손인준

Assignees

(주)일성도금

Dates

Publication Date: 20260512
Application Date: 20241105

Claims (9)

A pretreatment method for anodizing an aluminum alloy, characterized by including the step of performing cathodic oxidation treatment by applying a current density of -1 to -2 A/ dm² in a sulfuric acid solution to the aluminum alloy.
In Article 1, A pretreatment method for anodic oxidation treatment of an aluminum alloy, characterized in that the above sulfuric acid solution has a concentration of 10 to 40 percent.
In Article 1, A pretreatment method for anodic oxidation treatment of an aluminum alloy, characterized in that the step of performing the cathodic oxidation treatment is performed at a temperature of 20 to 70°C for 60 to 600 seconds.
In Article 1, A pretreatment method for anodic oxidation treatment of an aluminum alloy, characterized in that the step of performing the above cathodic oxidation treatment is performed in a 30% sulfuric acid solution at a temperature of 60 for 300 seconds.
In Article 1, A pretreatment method for anodizing an aluminum alloy, characterized by applying a current density of -1.156 A/ dm² .
Degreasing process for cleaning the surface of an aluminum alloy using acetone; Etching process involving immersion in a sodium hydroxide solution; De-smutting process for removing smut in a nitric acid solution after washing the etching solution; A cathodic oxidation process for performing cathodic oxidation treatment by applying a current density of -1 to -2 A/ dm² in a sulfuric acid solution; and An anodization process of immersing cathodic-treated aluminum alloy in sulfuric acid, oxalic acid, or phosphoric acid. A surface treatment method for an aluminum alloy characterized by including
In Article 6, The above sulfuric acid solution has a concentration of 10 to 40 percent, and A surface treatment method for an aluminum alloy, characterized in that the above cathodic oxidation treatment is performed at a temperature of 20 to 70°C for 60 to 600 seconds.
In Article 6, A surface treatment method for an aluminum alloy, characterized in that the above cathodic oxidation process is performed by applying a current density of -1.156 A/ dm² .
In Article 6, After the above anodic oxidation process: A coloring process using a dye on pores formed on the surface; and A sealing process containing inorganic substances such as nickel in the porous pore after the above coloring process. A surface treatment method for an aluminum alloy, characterized by further including

Description

Preprocessing method for anodizing of aluminum alloy The present invention relates to a pretreatment method for surface treatment of an aluminum alloy, and more specifically, to a cathodic oxidation treatment method for an aluminum alloy to remove silica (Si) components included in the aluminum alloy composition that cause defects during surface treatment, in order to reduce surface treatment defects caused by the influence of the alloy composition during anodic oxidation treatment of the aluminum alloy material. To enhance the physical properties of aluminum alloys, corrosion resistance and rust prevention characteristics are generally imparted to aluminum alloys with a high ionization tendency through methods such as plating, chemical treatment, anodizing, and painting. Aluminum alloys contain approximately 0.1–10% of alloying elements such as copper, silicon, magnesium, manganese, and zinc to enhance mechanical strength—including hardness, machinability, cutting ability, and toughness—or improve material properties through heat treatment, precipitation hardening, and age hardening, and are used as mechanical and structural materials. In addition to these improvements in mechanical strength, surface treatment is essential to impart corrosion resistance to aluminum alloys, which typically have low corrosion resistance. However, surface treatment involving chemical reactions of alloyed aluminum materials makes them vulnerable to corrosive environments due to surface defects caused by inorganic materials included as additives within the alloy. In particular, silicon, which possesses semiconductor properties, does not ionize in chemical substances other than hydrofluoric acid; consequently, it remains as a segregated material during surface treatment, causing a problem where chemical surface treatment fails due to differences in electrical properties. Accordingly, in order to achieve good surface treatment of aluminum alloys, there is a need for technology that can efficiently remove components from the surface that are not treated by chemical reactions, particularly silicon components. Figure 1 is a schematic diagram showing a surface treatment process of an aluminum alloy including the pretreatment method of the present invention. Figures 2 to 5 are surface SEM images of embodiments and control groups of the present invention. Figure 6 is a photograph showing the immersion test being performed according to an embodiment of the present invention. Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments and examples described herein. Furthermore, in order to clearly explain the invention in the drawings, parts unrelated to the description have been omitted, and similar parts throughout the specification have been given similar reference numerals. Throughout the specification of the present invention, when it is stated that a member is located "on" another member, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members. Throughout the specification of the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Throughout the specification of the present invention, terms of degree such as "about," "substantially," etc., are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the stated meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values are mentioned to aid in understanding the present invention. Throughout the specification of the present invention, terms of degree such as "a step of" or "a step of" do not mean "a step for." Throughout the specification of the present invention, the term “combination thereof” included in the Markush-style expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-style expression, and means including one or more selected from the group consisting of said components. Throughout the specification of the present invention, the description of "A and/or B" means "A or B, or A and B". The present invention relates to a pretreatment method for chemical surface treatment of an aluminum alloy, characterized by applying a reverse current to the aluminum alloy in a sulfuric acid solution to cathodic oxidize the aluminum alloy. Aluminum alloys improve mechanical strength by including alloying elements such as copper, silicon, magnesium, manganese, and zinc, but they have the pro